<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>一元运算符</title>
  </head>
  <body>
    <h2 style="font-size: 200px">&#9760;</h2>
    <script>
      var d = 20;
      console.log(d++ + ++d + d); // 20+22+22
    </script>
  </body>
</html>
